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- Haller, Sven, et al.
(författare)
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Caffeine impact on working memory-related network activation patterns in early stages of cognitive decline
- 2017
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Ingår i: Neuroradiology. - : Springer. - 0028-3940 .- 1432-1920. ; 59:4, s. 387-395
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Recent evidence indicates that caffeine may have a beneficial effect on cognitive decline and dementia. The current investigation assessed the effect of acute caffeine administration on working memory during the earliest stage of cognitive decline in elderly participants. Methods The study includes consecutive 45 elderly controls and 18 individuals with mild cognitive impairment (MCI, 71.6 +/- 4.7 years, 7 females). During neuropsychological follow-up at 18 months, 24 controls remained stable (sCON, 70.0 +/- 4.3 years, 11 women), while the remaining 21 showed subtle cognitive deterioration (dCON, 73.4 +/- 5.9 years, 14 women). All participants underwent an established 2-back working task in a crossover design of 200 mg caffeine versus placebo. Data analysis included task-related general linear model and functional connectivity tensorial independent component analysis. Results Working memory behavioral performances did not differ between sCON and dCON, while MCI was slower and less accurate than both control groups (p < 0.05). The dCON group had a less pronounced effect of acute caffeine administration essentially restricted to the right hemisphere (p < 0.05 corrected) and reduced default mode network (DMN) deactivation compared to sCON (p < 0.01 corrected). Conclusion dCON cases are characterized by decreased sensitivity to caffeine effects on brain activation and DMN deactivation. These complex fMRI patterns possibly reflect the instable status of these cases with intact behavioral performances despite already existing functional alterations in neocortical circuits.
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| 3. |
- Qian, Tianyi, et al.
(författare)
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Detecting Perfusion Pattern based on the Background Low-frequency Fluctuation in Resting-State Functional MRI Data and its Influence on Resting-State Networks : An Iterative Post-processing Approach.
- 2017
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Ingår i: Brain Connectivity. - : Mary Ann Liebert Inc. - 2158-0014 .- 2158-0022. ; 7:10, s. 627-634
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: RS-fMRI is based on the assumption that the vascular response and the blood oxygenation level dependent (BOLD) response are homogenous across the entire brain. However, this a priori hypothesis is not consistent with the well-known variability of cerebral vascular territories. In order to explore whether the RS networks are influenced by varied vascular speed in different vascular territories, we assessed the time-shift maps that give an estimate of the local timing of the vascular response and check whether local differences in this timing have an impact on the estimates of RS networks.METHODS: 217 elderly (>=60 years), healthy participants (73.74 ± 4.41 years, 143 female, 203 right-handed) underwent one MRI examination including an RS-fMRI session. After preprocessing, statistical analyses included time-shift analyses and RS-fMRI analyses using as regressor the delay maps obtained from the time-shift analyses. The functional connectivity map of default mode network of each participant was then calculated by using the seed-to-voxel analysis in the REST toolbox.RESULTS: Faster cerebrovascular responses were notably present in the primary motor and somatosensory and peri-insular cortex while slower responses were present in various regions including notably the posterior cingulate cortex (PCC). Moreover, significant changes notably in the default mode network (DMN), including medial pre-frontal cortex (t=11.95), posterior cingulate cortex (t=11.52), right middle temporal lobe (t=10.72) and right angular gyrus (t=10.88), were observed also taking into account the cerebrovascular delayed maps.DISCUSSION: As the most prominent example of the RS networks, DMN activation patterns change as a function of the cerebrovascular delay. These data suggest that a group correction for vascular maps in RS-fMRI measurements is essential to correctly depict functional differences and exclude potential confounding effects, notably in the elderly with increasing prevalence of vascular co-morbidity.
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| 4. |
- Zanchi, Davide, et al.
(författare)
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Decreased Fronto-Parietal and Increased Default Mode Network Activation is Associated with Subtle Cognitive Deficits in Elderly Controls
- 2017
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Ingår i: NeuroSignals (Print). - : S. Karger AG. - 1424-862X .- 1424-8638. ; 25:1, s. 127-138
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cognitive functions progressively deteriorate during aging and neurodegenerative diseases. The present study aims at investigating differences in working memory performance as well as functional brain changes during the earliest stages of cognitive decline in health elderly individuals.METHODS: 62 elderly individuals (41 females), including 41 controls (35 females) and 21 middle cognitive impairment subjects (6 females), underwent neuropsychological assessment at baseline and an fMRI examination in a N-back paradigm contrasting 2-back vs. 0-back condition. Upon a 18 months follow-up, we identified stable controls (sCON) with preserved cognition and deteriorating controls (dCON) with -1SD decrease of performances in at least two neuropsychological tests. Data analyses included accuracy and reaction time (RT) for the 2-back condition and general linear model (GLM) for the fMRI sequence.RESULTS: At the behavioral level, sCON and dCON performed better than MCI in terms of accuracy and reaction time. At the brain level, functional differences in regions of the fronto-parietal network (FPN) and of the Default Mode Network (DFM) were observed. Significantly lower neural activations in the bilateral inferior and middle frontal gyri were found in MCI versus both dCON / sCON and for dCON versus sCON. Significantly increased activations in the anterior cingulate cortex and posterior cingulate cortex and bilateral insula were found in MCI versus both dCON / sCON and in dCON versus sCON.CONCLUSION: The present study suggests that brain functional changes in FPN and DMN anticipate differences in cognitive performance in healthy elderly individuals with subsequent subtle cognitive decline.
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| 5. |
- Zanchi, Davide, et al.
(författare)
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Hippocampal and Amygdala Gray Matter Loss in Elderly Controls with Subtle Cognitive Decline
- 2017
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Ingår i: Frontiers in Aging Neuroscience. - : FRONTIERS MEDIA SA. - 1663-4365. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- In contrast to the idea that hippocampal and amygdala volume loss occur in late phases of neurodegeneration, recent contributions point to the relevance of preexisting structural deficits that are associated with aging and are independent of amyloid deposition in preclinical Alzheimer disease cases. The present work explores GM hippocampal and amygdala volumes in elderly controls displaying the first signs of cognitive decline. 455 subjects (263 females), including 374 controls (228 females) and 81 middle cognitive impairment subjects (35 females), underwent two neuropsychological evaluations (baseline and 18 months follow-up) and a MRI-T1 examination (only baseline). Clinical assessment included Mini-Mental State Examination (MMSE), Clinical Dementia Rating scale, Hospitalized Anxiety and Depression scale, the Consortium to Establish a Registry for Alzheimer's Disease neuropsychological battery and RI-48 Cued Recall Test (RI-48) for episodic memory. Based on their cognitive performance, we defined the controls as stable controls (sCON) and deteriorating controls (dCONs). Analyses included volumetric assessment, shape analyses and linear regressions between GM volume loss and differences in clinical scores between baseline and follow-up. Significant GM volume decrease in hippocampus bilaterally and right amygdala was found in dCON compared to sCON (p < 0.05). Lower right amygdala volumes were measured in mild cognitive impairment (MCI) compared to sCON (p < 0.05). Shape analyses revealed that atrophy was more pronounced at the superior-posterior lateral side of the hippocampus and amygdala. Significant correlations were found between GM volume of left hippocampus and the delta of MMSE and RI-48 scores in dCON and MCI groups separately. Decreased hippocampal and right amygdala volumes precede the first signs of cognitive decline in healthy elderly controls at the pre-MCI state. Left hippocampus volume may also predict short-term changes of overall cognition in these vulnerable cases.
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